The process consists of four stages: the preparation phase, the pre-blowing phase, the ignition phase, and the normal combustion phase.

Preparation Phase: After the controller is powered on, it begins an internal program self-check. Simultaneously, the servo motor drives the air door to the closed position. Once the self-check is complete, the controller is in standby mode. When the thermostat, high/low gas pressure switches, and steam boiler steam pressure switches allow, the controller starts up and enters the pre-blowing phase. If the solenoid valve assembly is equipped with a leak detection system, this system will first perform a valve leak check when the above switches allow, and only after passing the check will it proceed to the pre-blowing phase.

During the pre-blowing stage: the servo motor drives the air door to the full-open flame position, while the fan motor starts, initiating a 13-second blowing cycle to introduce air for pre-blowing. Depending on the programmable controller, the blowing continues for approximately 20 to 40 seconds before the servo motor drives the air door to the ignition opening position, preparing for ignition. Throughout the pre-blowing stage, the air pressure switch measures the air pressure, and the pre-blowing process can only continue if the air pressure remains at a sufficiently high level.

Ignition Phase: After the servo motor drives the air door to the ignition opening position, the ignition transformer activates and supplies high voltage to the ignition electrode to produce an ignition spark. Approximately 3 seconds later, the programmable controller powers the safety solenoid valve and the proportional solenoid valve. Once the valves open, gas reaches the combustion head, mixes with air provided by the fan, and is then ignited. Within 2 seconds after the valve opens, the ionization electrode should detect the presence of flame. Only then will the programmable controller proceed to the next step. Otherwise, the controller locks and de-energizes the solenoid valves to stop gas supply, while simultaneously triggering an alarm. (Ignition during motor startup)

During the normal combustion phase: After the ignition is normal and the flame stabilizes for a few seconds, the servo motor drives the air door to the full-burn position, (the fuel pump of the engine opens and starts to spray fuel) simultaneously, the servo motor of the proportional gas regulator valve is engaged, and it adjusts the gas pressure after the valve based on air pressure and furnace back pressure to regulate the gas flow, aiming for stable and efficient combustion. Subsequently, the burner automatically adjusts between full and low flame and shuts down according to the requirements of various limit switches.

Furthermore, during the entire combustion process, the ionization electrode and the air pressure switch monitor the burner.